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THE BLESBOK

23 May 2013

QUICK FACTS

Scientific Name : Damaliscus pygargus phillipsi

Weight (Ram) : 75kg

Weight: (Ewe) : 65kg

Shoulder height (Ram) : 95cm

Shoulder height (Ewe) : 93cm

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The blesbok Damaliscus pygargus phillipsi and the bontebok Damaliscus pygargus pygargus are subspecies of Damaliscus pygargus which only occurs in South Africa. Damaliscus pygargus was first described as Antilope pygargus by Pallas in 1767 based on a bontebok that was collected from near the Swart River in Caledon, Western Cape, but the name Damaliscus was created in 1894 by Sclater and Thomas because Antilope only occurs in India. The blesbok was first described as Damaliscus phillipsi by Harper in 1939 based on a specimen that was shot in the Free State. Only later was it realized that the bontebok and blesbok are subspecies of Damaliscus pygargus. A fossil ancestor Damaliscus nilo lived at Sterkfontein in Gauteng until some 12 000 years ago, while other early fossil forms of Damaliscus date back some 2 million years. There are four species of Damaliscus at present in southern and eastern Africa.

www.leopard.tvThe blesbok was originally limited to the eastern and central grassland plains of South Africa but has been widely introduced elsewhere. Historically there was a gap of some 300 km between the southernmost blesbok and the northernmost bontebok. The blesbok became extinct in KwaZulu-Natal in the first decade of the 20th century but has since been reintroduced there.

The blesbok is a medium-sized antelope with various morphological and genetic differences from the bontebok. In appearance, a white blaze covers the forehead and muzzle in 81% of all bontebok, but in the blesbok this blaze is always broken by a dark band just below the eyes. The blesbok also has a reddish-brown coat colour as opposed to the rich, dark brown one of the bontebok; the fronts of the legs of a blesbok are mostly dark brown, while the legs are white from below the knee in the bontebok; and the horns of the blesbok have straw-coloured upper surfaces on the rings in contrast to black ones in the bontebok. The most obvious consistent difference is the pale brown patch on the buttock of the blesbok as opposed to the white one of the bontebok. Both sexes of both subspecies have lyre-shaped horns. The mean shoulder height of an adult blesbok ram is 95 cm and the weight is 75 kg as opposed to 93 cm and 65 kg in an adult ewe.

www.leopard.tvThe ideal habitat is the high-lying central and eastern grasslands of South Africa that receive a mean annual rainfall of 400 to 800 mm. Blesbok are patch-selective, short grass grazers that feed at a height of 200 to 600 mm above the ground and can create overgrazing problems. They rapidly move on to recently burned grasslands. The annual diet consists of 99% grass and 1% browse and forbs, but they may sometimes eat more browse. Blesbok eat grasses in the dry season that they would not touch in the wet season. They are water dependent, prefer natural waterholes, and drink about 3 litres of water per day in the daytime. The blesbok is gregarious and diurnally active, forming breeding herds consisting of 10 to 25 ewes per territorial ram. It forms large bachelor herds and activity is reduced during hot weather. Blesbok walk in a single file when going to water or feeding patches. The herd structure changes through the year whereas that of the bontebok remains stable. The dominant blesbok ram is territorial and has a mean territory size of 2.3 ha (range: 0.9 to 4.1 ha) while the range of the breeding herd varies from 150 to 400 ha. Territorial rams create dung middens, often on old termite mounds, and lie up on them when resting. Blesbok also have interdigital glands that may possibly be used in territorial marking.

www.leopard.tvBoth sexes become sexually mature at an age of 28 months. The estrus cycle lasts 28 to 32 days and gestation lasts 7 to 8 months. Following mating in March and April, single cream-coloured lambs that weigh 6 to 7 kg at birth are born from November to January, peaking in December. The lamb is active within 20 minutes of birth when it can run around with its mother. The lamb grows rapidly in its first year of life after which the growth rate tapers off. The ewe has two mammae and the interval between lambs is 12 months. The natural population growth rate can be as high as 55% depending on rainfall and veld condition and the life expectancy in the wild is 12 years.

The blesbok easily hybridises with the bontebok to produce fertile hybrids, and with the tsessebe and red hartebeest to produce infertile ones. Because it is an adaptable, large herd animal the blesbok is often used on wildlife ranches with large predators to buffer rarer wildlife against predation.

 

References:

Grubb, P. 2005. Order Artiodactyla. In D E Wilson and D M Reeder (Eds), Mammal species of the world – a taxonomic and geographic reference, third edition. Baltimore: Johns Hopkins University Press, 676 – 677.

Skinner, J D and C T Chimimba (Eds) 2005. The mammals of the southern African subregion, third edition. Cambridge: Cambridge University Press, pp 653 – 658.

article by: Prof J du P Bothma

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